DESIGN, ANALYSIS, AND RELIABILTY OF SOLAR PANEL ROTATION MECHANISM FOR MICROSATELLITE

Solar array rotation mechanism provides a hinged joint between the solar panel and satellite body, smooth rotation of the solar array into deployed position and its fixation in this position. After unlocking of solar panel (while in orbit), rotation bracket turns towards ready-to-work position under the action of driving spring. During deployment, once reached the required operating angle (defined by power subsystem engineer), the rotation bracket collides with the fixed bracket that is mounted on body of the satellite, to stop rotation. Due to the effect of collision force that may alter the rotation mechanism function, design of centrifugal brake is essential. At stoppage moment micro-switches activate final position sensor and a stopper locks the rotation bracket. Design of spring and centrifugal brake components, static finite element stress analysis of primary structure body of rotation mechanism at stoppage moment have been obtained. Last, reliability analysis of rotation mechanism is evaluated. The benefit of this study is to aid in the design of rotation mechanism that can be used in micro-satellite applications.

Thermal Deformation Analysis of Micro satellite Structure

Mounting accuracy of satellite payload and ADCS (attitude determination and control subsystem) seats is one of the requirements to achieve the satellite mission with acceptable performance. Components of mounting inaccuracy are technological inaccuracies, residual plastic deformations after loading (during transportation and orbital insertion), elastic deformations, and thermal deformations during orbital operation. This paper focuses on estimation of thermal deformations of satellite structure. Thermal analysis is executed by applying finite-difference method (IDEAS) and temperature profile for satellite components case is evaluated. Then, Perform thermal finite-element analysis applying the finite-difference model results as boundary conditions; and calculate the resultant thermal strain. Next, applying the resultant thermal strain, perform finite-element structure analysis to evaluate structure deformations at the payload and ADCS equipments seats.

A Generic Reference Software Architecture for Load Balancing over Mirrored Web Servers: NaSr Case Study

With the rapid expansion of the internet and the increasing demand on Web servers, many techniques were developed to overcome the servers' hardware performance limitation. Mirrored Web Servers is one of the techniques used where a number of servers carrying the same "mirrored" set of services are deployed. Client access requests are then distributed over the set of mirrored servers to even up the load. In this paper we present a generic reference software architecture for load balancing over mirrored web servers. The architecture was designed adopting the latest NaSr architectural style [1] and described using the ADLARS [2] architecture description language. With minimal effort, different tailored product architectures can be generated from the reference architecture to serve different network protocols and server operating systems. An example product system is described and a sample Java implementation is presented.

Shifting Ground:Beyond National Architecture

The Irish Pavilion at the Venice Architecture Biennale 2012 charts a position for Irish architecture in a global culture where the modes of production of architecture are radically altered. Ireland is one of the most globalised countries in the world, yet it has developed a national culture of architecture derived from local place as a material construct. We now have to evolve our understanding in the light of the globalised nature of economic processes and architectural production which is largely dependent on internationally networked flows of products, data, and knowledge. We have just begun to represent this situation to ourselves and others. How should a global architecture be grounded culturally and philosophically? How does it position itself outside of shared national reference points?
heneghan peng architects were selected as participants because they are working across three continents on a range of competition-winning projects. Several of these are in sensitive and/or symbolic sites that include three UNESCO World Heritage sites, including the Grand Egyptian Museum in Cairo, the Giants Causeway Visitor Centre in Northern Ireland, and the new Rhine Bridge near Lorelei.
Our dialogue led us to discussing the universal languages of projective geometry and number are been shared by architects and related professionals. In the work of heneghan peng, the specific embodiment of these geometries is carefully calibrated by the choice of materials and the detailed design of their physical performance on site. The stone facade of the Giant’s Causeway Visitor Centre takes precise measure of the properties of the volcanic basalt seams from which it is hewn. The extraction of the stone is the subject of the pavilion wall drawings which record the cutting of stones to create the façade of the causeway centre.
We also identified water as an element which is shared across the different sites. Venice is a perfect place to take measure of this element which suggests links to another site – the Nile Valley which was enriched by the annual flooding of the River Nile. An ancient Egyptian rod for measuring the water level of the Nile inspired the design of the Nilometre - a responsive oscillating bench that invites visitors to balance their respective weights. This action embodies the ways of thinking that are evolving to operate in the globalised world, where the autonomous architectural object is dissolving into an expanded field of conceptual rules and systems. The bench constitutes a shifting ground located in the unstable field of Venice. It is about measurement and calibration of the weight of the body in relation to other bodies; in relation to the site of the installation; and in relation to water. The exhibit is located in the Artiglierie section of the Arsenale. Its level is calibrated against the mark of the acqua alta in the adjacent brickwork of the building which embodies a liminal moment in the fluctuating level of the lagoon.
The weights of bodies, the level of water, changes over time, are constant aspects of design across cultures and collectively they constitute a common ground for architecture - a ground shared with other design professionals. The movement of the bench required complex engineering design and active collaboration between the architects, engineers and fabricators. It is a kind of prototype – a physical object produced from digital data that explores the mathematics at play – the see-saw motion invites the observer to become a participant, to give it a test drive. It shows how a simple principle can generate complex effects that are difficult to predict and invites visitors to experiment and play with them.

Between Order and Modernity: Resurgence Planning in Revolutionary Egypt

Egypt’s Revolution of 1952 presented a major historical change to its political and economic structure, its society, and its institutions. This paper examines how Nasser’s regime operated through the state apparatus to exhibit features of modernity. Under the pretext of modernization, renovating Cairo’s authentic urban fabric was one of the channels that displayed the new ambitions to unveil a centralized system of governance and ideologies of socialism. The paper particularly looks at the city’s resurgence attempts, promoted by upgrading practices that displayed Western ideals of planning. Eventually, the contradictory planning legislative system introduced by the government raised early alarms at the problems encountered in the planning institution that was not only unable to liberate Cairo’s urban districts from its long-rooted decay, but also struggled to implement the regime’s flagship policy of social justice in a context wherein it was much needed.

The Disrupted Space: Safety and Security in traditional contexts

One of the core elements of successful planning is the individuals’ experience of their shared open spaces. This paper attributes to the relationship between safety and urban design by means of natural surveillance and security in the city’s shared spaces. It examines how political claims over space reassembled alternative definitions of security in one of Cairo’s oldest quarters, and how ambitious planning schemes were mostly driven by problems of insecurity, chaos and disorder. The main crux to this account is based on original documents, interviews and maps which reveals considerable insights and accounts of how this vision affected the quarter’s spatial quality and the user’s reactions to his new spatial formula. It also reveals conflicting conceptions of safety and security between the planning ambitions and the users experiences, which not only lacked reliable visions for securing the quarter, but also resulted further disruption to their everyday living spaces.

Chase over the Nile: The Social Evolution of Riverine Landscape in Urban Egypt

Throughout its history, Cairo evolved as a regional metropolis that sprawls along the banks of the Nile accumulating narratives of evolving social landscape. Overlooking the Nile reflected a privileged social position and place for the urban elite. In spatial terms, the urban bourgeoisie tend to develop living havens in enclaves that are distant from the populace’s everyday life. Ironically, exclusive settlements only attract urban growth further in their direction. This chapter offers an analytical reading of the socio-spatial structure of Cairo following the emergence and decline of a series bourgeoisie quarters along the shores of the Nile. It reports urban narratives based on archival records, documents and investigation of historical texts and travelers’ accounts. This essay argues that cities are essentially social constructs in which hierarchy and connectivity are fundamental aspects of its economic and spatial logic. Through social ambition and desire for upgrade, middle class infiltrate into bourgeoisie havens and sometimes encircle it, seeking better living condition inscribed by social mobility and connectivity to centres of wealth and power. Being both natural barrier and cohesive spine, the Nile helped Cairo to develop successive nucleuses of highly crafted urban experiences that have left their imprints on the contemporary urban scene.

The Modern Ordinary: Changing culture of living in Egypt’s traditional quarters at the turn of the twentieth Century

Having experienced social and political structures of the 19th century Europe, Western- educated Egyptian elite used public institutions to force legislative structures and procedures that ruled out traditional housing forms and spatial systems. This essay detects direct and indirect impact of these changes that informed the spatial change of modern living in Egypt in the first quarter of the twentieth century. It offers analysis of socio-spatial practices and change in ordinary Cairenes’ modes of everyday living, using social routine and interaction to explain spatial systems and changing house forms during the first quarter of the 20th century. In doing so, the essay utilized archival documents, accounts, formal decrees, and novels of the time as well as conducting survey of house forms and spatial organizations in Old Cairo.

Sequence stratigraphy related distribution of diagenetic alterations In Miocene deltaic and shoreface arenites, the Suez Rift, EGYPT.

The distribution of eogenetic alterations in shoreface-offshore and coarse-grained deltaic, calcarenite to hybrid arenites of the Mheiherrat Formation (lower Rudeis), Early Miocene, the Gulf of Suez, Egypt) can be constrained within a sequence stratigraphic framework. The bioclast-rich, shoreface (trangressive systems tract; TST) and shoreface (highstand systems tract; HST) arenites, particularly those below the parasequence boundaries and maximum flooding surface, are cemented by grain-coating microcrystalline, circumgranular isopacheous acicular and columnar, and coarse-crystalline calcite (δ18OVPDB = -3.6 to -0.3 ‰; δ13CVPDB = -2.3 to -0.7 ‰), non-Ferro an dolomite (δ18OVPDB = -3.9 to +0.9‰; δ13CVPDB = -2.5 ‰ to -0.7 ‰), and pyrite. Zeolite, palygorskite and gypsum occur in the HST shoreface arenites, being enhanced by aird climatic condations. The coarse-grained deltaic LST deposits are pervasively cemented by coarse-crystalline, pore-filling calcite and small amounts of microcrystalline calcite (δ18OVPDB = -4.4 to -2.3 ‰; δ13CVPDB = -2.8 to -1.3 ‰) and non-ferroan dolomite (δ18OVPDB = -4.8 to -2.5 ‰; δ13CVPDB = -3.3 to -1.5 ‰). Thus, this study demonstrates that changes in pore-water chemistry, which induced changes in the texture, composition and extent of cementation in the Miocene arenites was controlled by changes in the relative sea level and by the paleo-climatic conditions during deposition of the HST arenites.

Sequence stratigraphy related distribution of diagenetic alterations In Miocene deltaic and shoreface arenites, the Suez Rift, EGYPT.. Available from: https://www.researchgate.net/publication/264545153_Sequence_stratigraphy_related_distribution_of_diagenetic_alterations_In_Miocene_deltaic_and_shoreface_arenites_the_Suez_Rift_EGYPT [accessed Apr 15, 2015].

(Re) making trajectories: Eviction, control and power

The City of Cairo's experienced a major shift in its urban planning attitude and practice since the mid 1970s which mostly validated elements of economic planning while neutralizing its social aspects. This ad hoc approach escalated conflict in planning politics over the control of space between tiers of the planning institution and the locals leading to rigorous planning actions among major stakeholders such as eviction and control of spaces. The article examines how institutional claims over space reassembled alternative definitions of quality of life in one of Cairo's oldest quarters, and how ambitious planning schemes were mostly driven by entrepreneurial rather than societal. Based on first-hand interviews and visuals, the article aims to reveal the local's struggle to survive such interventions with attention to their daily negotiations in place.

Wounded Spaces: When Planning Degraded Cairo’s Urban Memory

This paper examines the position of planning practices operated under precise guidelines for displaying modernity. Cultivating the spatial qualities of Cairo since the 1970s has unveiled centralised ideologies and systems of governance and economic incentives. I present a discussion of the wounds that result from the inadequate upgrading ventures in Cairo, which I argue, created scars as enduring evidence of unattainable planning methods and processes that undermined its locales. In this process, the paper focuses on the consequences of eviction rather than the planning methods in one of the city’s traditional districts. Empirical work is based on interdisciplinary research, public media reports and archival maps that document actions and procedures put in place to alter the visual, urban, and demographic characteristics of Cairo’s older neighbourhoods against a backdrop of decay to shift towards a global spectacular. The paper builds a conversation about the power and fate these spaces were subject to during hostile transformations that ended with their being disused. Their existence became associated with sores on the souls of its ex-inhabitants, as outward signs of inward scars showcasing a lack of equality and social justice in a context where it was much needed.

Land cover mapping analysis and urban growth modeling using remote sensing techniques

The rapid growth of big cities has been noticed since 1950s when the majority of world population turned to live in urban areas rather than villages, seeking better job opportunities and higher quality of services and lifestyle circumstances. This demographic transition from rural to urban is expected to have a continuous increase. Governments, especially in less developed countries, are going to face more challenges in different sectors, raising the essence of understanding the spatial pattern of the growth for an effective urban planning. The study aimed to detect, analyse and model the urban growth in Greater Cairo Region (GCR) as one of the fast growing mega cities in the world using remote sensing data. Knowing the current and estimated urbanization situation in GCR will help decision makers in Egypt to adjust their plans and develop new ones. These plans should focus on resources reallocation to overcome the problems arising in the future and to achieve a sustainable development of urban areas, especially after the high percentage of illegal settlements which took place in the last decades. The study focused on a period of 30 years; from 1984 to 2014, and the major transitions to urban were modelled to predict the future scenarios in 2025. Three satellite images of different time stamps (1984, 2003 and 2014) were classified using Support Vector Machines (SVM) classifier, then the land cover changes were detected by applying a high level mapping technique. Later the results were analyzed for higher accurate estimations of the urban growth in the future in 2025 using Land Change Modeler (LCM) embedded in IDRISI software. Moreover, the spatial and temporal urban growth patterns were analyzed using statistical metrics developed in FRAGSTATS software. The study resulted in an overall classification accuracy of 96%, 97.3% and 96.3% for 1984, 2003 and 2014’s map, respectively. Between 1984 and 2003, 19 179 hectares of vegetation and 21 417 hectares of desert changed to urban, while from 2003 to 2014, the transitions to urban from both land cover classes were found to be 16 486 and 31 045 hectares, respectively. The model results indicated that 14% of the vegetation and 4% of the desert in 2014 will turn into urban in 2025, representing 16 512 and 24 687 hectares, respectively.

Modelling and simulation of a photovoltaic fuel cell hybrid system

A stand-alone power system is an autonomous system that supplies electricity to the user load without being connected to the electric grid. This kind of decentralized system is frequently located in remote and inaccessible areas. It is essential for about one third of the world population which are living in developed or isolated regions and have no access to an electricity utility grid. The most people live in remote and rural areas, with low population density, lacking even the basic infrastructure. The utility grid extension to these locations is not a cost effective option and sometimes technically not feasible. The purpose of this thesis is the modelling and simulation of a stand-alone hybrid power system, referred to as “hydrogen Photovoltaic-Fuel Cell (PVFC) hybrid system”. It couples a photovoltaic generator (PV), an alkaline water electrolyser, a storage gas tank, a proton exchange membrane fuel cell (PEMFC), and power conditioning units (PCU) to give different system topologies. The system is intended to be an environmentally friendly solution since it tries maximising the use of a renewable energy source. Electricity is produced by a PV generator to meet the requirements of a user load. Whenever there is enough solar radiation, the user load can be powered totally by the PV electricity. During periods of low solar radiation, auxiliary electricity is required. An alkaline high pressure water electrolyser is powered by the excess energy from the PV generator to produce hydrogen and oxygen at a pressure of maximum 30bar. Gases are stored without compression for short- (hourly or daily) and long- (seasonal) term. A proton exchange membrane (PEM) fuel cell is used to keep the system’s reliability at the same level as for the conventional system while decreasing the environmental impact of the whole system. The PEM fuel cell consumes gases which are produced by an electrolyser to meet the user load demand when the PV generator energy is deficient, so that it works as an auxiliary generator. Power conditioning units are appropriate for the conversion and dispatch the energy between the components of the system. No batteries are used in this system since they represent the weakest when used in PV systems due to their need for sophisticated control and their short lifetime. The model library, ISET Alternative Power Library (ISET-APL), is designed by the Institute of Solar Energy supply Technology (ISET) and used for the simulation of the hybrid system. The physical, analytical and/or empirical equations of each component are programmed and implemented separately in this library for the simulation software program Simplorer by C++ language. The model parameters are derived from manufacturer’s performance data sheets or measurements obtained from literature. The identification and validation of the major hydrogen PVFC hybrid system component models are evaluated according to the measured data of the components, from the manufacturer’s data sheet or from actual system operation. Then, the overall system is simulated, at intervals of one hour each, by using solar radiation as the primary energy input and hydrogen as energy storage for one year operation. A comparison between different topologies, such as DC or AC coupled systems, is carried out on the basis of energy point of view at two locations with different geographical latitudes, in Kassel/Germany (Europe) and in Cairo/Egypt (North Africa). The main conclusion in this work is that the simulation method of the system study under different conditions could successfully be used to give good visualization and comparison between those topologies for the overall performance of the system. The operational performance of the system is not only depending on component efficiency but also on system design and consumption behaviour. The worst case of this system is the low efficiency of the storage subsystem made of the electrolyser, the gas storage tank, and the fuel cell as it is around 25-34% at Cairo and 29-37% at Kassel. Therefore, the research for this system should be concentrated in the subsystem components development especially the fuel cell.

Entwicklung eines Bewertungssystems für die Aschuaiat-Gebiete mit Hilfe des Geographischen Informationssystems (GIS) am Beispiel des Stadtteils Manshiet Nasser in Kairo

Der Schwerpunkt dieser Arbeit handelt sich um die informelle Siedlungen in Kairo (die wir Asch- Gebiete nennen). Der Begriff "Aschuaiat" bezeichnet ganz speziell und treffend dieses Phänomen. Die Probleme der Aschuaiat haben seit den 70er Jahren auf ganz Ägypten und die Stadt Kairo sehr negative Auswirkungen, die im Laufe der Zeit zu massiven Problemen geworden sind. Die Entscheidungsträger versuchten für diese Schwierigkeiten Lösungen zu finden, aber die Ergebnisse waren nicht befriedigend. Dieses Phänomen sieht wie ein städtebauliches Problem aus, kann aber in Wirklichkeit nicht von den ökologischen und sozialen Verhältnisse einer Region getrennt werden. Die Aschuaiat entstehen normalerweise in städtebaulichen Zentren und in größeren Städten als Ergebnisse ihrer Anziehungskraft, da solche Städte ein gutes Angebot an Arbeitsplätzen, insbesondere im Bereich der Dienstleistungen, haben. Im Gegensatz dazu stehen die landwirtschaftlichen Gebiete: sie zeichnen sich insbesondere durch steigende Arbeitslosigkeit und Mangel an Dienstleistungen aus. Deshalb wandert ein Großteil der Bevölkerung vom Land in die Stadt ab, um hier auf die Suche nach einem Arbeitsplatz zu gehen und insgesamt bessere Lebensbedingungen vorzufinden. Die Zahl der Zuwanderer steigt stetig; die Städte können die Bedürfnisse der Bevölkerung an Angeboten für Wohnungen, Arbeitsplätzen und Dienstleistungen nicht erfüllen. Deswegen nimmt die Bevölkerung, ihre Probleme selbst in die Hand. Dies führt in den meisten Fällen zu einer klaren Form von Aschuaiat innerhalb und um die städtebaulichen Zentren herum. Die Anzahl der Aschuaiat, die sich rings um Kairo befinden, beträgt 76 Zonen mit einer Gesamtfläche von 23,10 km² und einer Einwohnerzahl von 2.098.469. Die Anzahl der illegalen Wohnungseinheiten beträgt 70 Prozent des Gesamtwertes legaler, staatlicher oder privater Wohneinheiten. Diese wurden im Zeitraum zwischen 1980 und 2000 erbaut. Jede Provinz in Ägypten hat Asch-Gebiete - mit Ausnahme der Provinzen Süd Sina und Neues Tal. Die meisten konzentrieren sich in den Provinzen El Dakahlia (121) und Dumiat (88). Die wenigsten Asch-Gebiete (jeweils nur eine Zone) gibt es in den Provinzen Rotes Meer und Nord Sina. In Ägypten wird die Einwohnerzahl der Aschuaiat auf 37 Prozent der Gesamtbevölkerung der städtebaulichen Gebiete geschätzt. Über die genaue Anzahl der Aschuaiat liegen jedoch keine zuverlässigen Informationen vor, die statistischen Daten der staatlichen Organisationen weisen unterschiedliche Resultate auf. Das Ministerium für lokale Entwicklung verkündete, dass die Zahl der Aschuaiat im Jahr 2000 ca. 916 und im Jahr 2003 ca. 1.228 Zonen betragen hat; das Informationszentrum zur Unterstützung von Sachentscheidungen registrierte jedoch für das Jahr 2000 eine Zahl von 1.034 Zonen; demgegenüber liegt die von CAPMAS registrierte Anzahl für 2000 bei 909 Zonen. Diese Unterschiede in der Erfassung der statistischen Daten kann darauf zurückgeführt werden, dass es in Ägypten keine einheitliche Definition für Aschuaiat gibt. Dieses Problem verstärkt den Bedarf an geeignetem Bewertungssystem für die Bewertung der Qualität solcher Gebiete in ganz Ägypten. Das vorgeschlagene Bewertungssystem basiert auf der Analyse und Bewertung der Hauptstrukturen, die die eigentliche Zusammensetzung einer Siedlung repräsentieren. Diese Strukturen spiegeln in der Regel die sozialen, städtebaulichen und infrastrukturellen Eigenschaften eines Gebietes wider. Konkret befasst sich diese Untersuchung mit den verschiedenen Strukturen, die die Lebens- und Siedlungsqualität in den Aschuaiat beeinflussen.